Eating at night may be associated with depression- and anxiety-like moods compared to having daytime meals, according to a study.

The study, published in the journal Proceedings of the National Academy of Sciences, examined the effects of eating during the day and at night as opposed to solely during the day.

The researchers found that among individuals in the daytime and nighttime eating groups, anxiety- and depression-like mood levels rose by 16 per cent and 26 per cent, respectively.

This increase was not seen in the group of participants who only ate during the day, indicating that meal timing may affect mood vulnerability, they said.

"Our findings provide evidence for the timing of food intake as a novel strategy to potentially minimise mood vulnerability in individuals experiencing circadian misalignment, such as people engaged in shift work, experiencing jet lag, or suffering from circadian rhythm disorders," said study co-corresponding author Frank A. J. L. Scheer from Brigham and Women's Hospital, US.

"Future studies in shift workers and clinical populations are required to firmly establish if changes in meal timing can prevent their increased mood vulnerability. Until then, our study brings a new 'player' to the table: the timing of food intake matters for our mood", Scheer said.

The findings open the door for a novel sleep behavioral strategy that might also benefit individuals experiencing mental health disorders.

The study adds to a growing body of evidence finding that strategies that optimise sleep and circadian rhythms may help promote mental health.

The researchers enrolled 19 participants - 12 men and 7 women - for a randomised controlled study.

Participants were kept in dim light for four 28-hour days, such that by the fourth day their behavioral cycles were inverted by 12 hours, simulating night work and causing circadian misalignment.

Participants were randomly assigned to one of two meal timing groups: the daytime and nighttime meal control group, which had meals according to a 28-hour cycle, and the daytime-only meal intervention group, which had meals on a 24-hour cycle.

The researchers assessed depression- and anxiety-like mood levels every hour. They found that meal timing significantly affected the participants' mood levels.

During the simulated night shift (day 4), those in the daytime and nighttime meal control group had increased depression-like mood levels and anxiety-like mood levels, compared to day 1.

In contrast, there were no changes in mood in the daytime meal intervention group during the simulated night shift. Participants with a greater degree of circadian misalignment experienced more depression- and anxiety-like moods.

"Meal timing is emerging as an important aspect of nutrition that may influence physical health," said Sarah L. Chellappa, who is now at the University of Cologne in Germany.

"But the causal role of the timing of food intake on mental health remains to be tested. Future studies are required to establish if changes in meal timing can help individuals experiencing depressive and anxiety/anxiety-related disorders," Chellappa added.